INIr. C. G. Williams on Products from Boghead Coal. 135 



obtained to be the radical of the butylic alcohol. The density of the 

 fluid, and the temperature at which it distils, are also rather in 

 favour of this view. It will be seen that 243° F. should be the 

 boiling-point of butyle if Frankland's determination of that of amyle 

 be correct, and Kopp's law hold with these bodies. 



A careful study of the papers already published on the radicals of 

 this series, shows that more than one anomaly appears to exist in 

 their physical properties, the gradations usually observed in homo- 

 logous groups not being so distinctly marked as with most others, 

 and this fact somewhat impedes their identification. The large 

 quantity of substance which becomes at our disposal from the source 

 mentioned, will, by facilitating the study, throw light on these points. 



I believe I shall be able to isolate at least four of the radicals, viz. 

 propyle, butyle, amyle, and caprotyle, from the coal distillate. The 

 per-centage composition varying so little with the different homo- 

 logues, I rely chiefly on vapour density and products of decomposi- 

 tion as the means of proving their presence. 



The hydrocarbons accompanying the radicals are also quite distinct 

 from the benzole series, as shown by the low density of the nitro- 

 compound. The latter is extremely difficult of reduction by sulphide 

 of ammonium or protacetate of iron, but it furnishes a volatile oily 

 alkaloid by distillation with an alcoholic solution of potash. 



The tedious purifications and the numerous operations required 

 before the substances can be obtained in a state of sufficient purity 

 for analysis from the coal distillate, will probably cause a consider- 

 able period to elapse before a detailed account of all the bodies can 

 be published. 



"On Peristaltic Induction of Electric Currents." By Professor 

 WiUiam Thomson, F.R.S. 



Recent observations on the propagation of electricity through wires 

 in subaqueous and subterranean telegraphic cables have brought to 

 light phenomena of induced electric currents, which, while they are 

 essentially different from the phenomena of what has hitherto been 

 called electro-dynamic induction, are exactly such as might have been 

 anticipated from the well-established theory of electrical equilibrium, 

 had experiment afforded the data of relation between electrostatical 

 and electro-dynamic units wanted for determining what dimensions 

 of wire would be required to render these phenomena sensible to 

 ordinary observation. They present a very perfect analogy with the 

 mutual influences of a number of elastic tubes bound together late- 

 rally throughout their lengths, and surrounded and filled with a 

 liquid which is forced through one or more of them, while the others 

 are left with their ends 0{)en {uninsulated), or stopped {insulated), or 

 subjected to any other particular conditions. The hydrostatic press- 

 ure applied to force the liquid through any of the tubes will cause 

 them to swell and to press against the others, which will thus, by 

 peristaltic action, compel the li(|uid contained in them to move, in 

 different parts of them, iu one direction or the other. A long solid 

 cylinder of an incompressible clastic solid*, bored out symmetrically 



* Such as india-rubber very approximately is in reality. 



